I launched a small site using D3 (windhistory.com). It's great. SVG is now supported in Firefox, Chrome, IE, and Mobile Safari. The big limitation is IE7 and IE8, but if you can blow those users off SVG is fantastic.
Unfortunately, I can't yet blow those users off. The last set of visualizations I did with Protovis saw over 20% of its traffic in IE < 9. I'd be ecstatic if I could ignore VML...
Your site breaks the back button worse than any site I've ever encountered. I found that to be incredibly annoying, but I think I would have liked the site if it weren't for that.
